This invention relates to a mechanism for stopping operation of a poppet valve which is used as an intake valve, an exhaust valave or the like in an internal combustion engine in particular.
As one example, there is an internal combustion engine provided with two (primary and secondary) intake valves in one cylinder, in which during low-loaded or medium-loaded driving range of the engine, only the primary intake valve is operated, having the secondary intake valve stopped, and during high-loaded during range of the engine, both the primary valve and the secondary valve are operated to increase the output of the engine. Also, in a multi-cylinder internal combustion engine, it is proposed to control operation of the intake and exhaust valves according to the driving conditions of the engine, namely, during idling or low-loaded driving range where operation of all the cylinders are not necessarily required, the intake and exhaust valves of some of the cylinders are stopped to rest said cylinders, thereby reducing fuel consumption, and during high-loaded driving range, all the intake and exhaust valves are operated to activate all the cylinders.
As one example of a mechanism for stopping operation of the valve, it is proposed to define a clearance in a part of a valve actuating system and a solid stopper is moved into and out of the clearance to mechanically stop operation of the valve. This mechanism has advantages in that by moving said stopper in a direction substantially perpendicular to the operating direction of the valve, any imperfect lift of the valve can be prevented and that said stopper can be moved into and out of the clearance only when a lift of a cam for actuating said valve is in a zero range.
However, there is a disadvantage in that if said stopper is moved into and out of the clearance at the nearest point to a start of the cam lift in the zero range, a valve lift might be started before the stopper is completely moved into or out of the clearance and an excessively high stress may be imposed on a part of the stopper, causing breakage of the stopper and generation of noise.